Patrocinador

Resumen

The integration of geophysical and geological methods is a sound means of
studying cavities that are not accessible from the surface. In this Ph.D. Thesis, cavities
under different geological, size and depth conditions were studied to establish the
suitability of different techniques for void detection and characterization. The Gruta de
las Maravillas cave, located within pyrite-bearing marbles in the Cerro del Castillo hill
(Aracena, SW Spain), was explored through a combination of techniques: microgravity,
magnetic, electrical resistivity tomography (ERT), induced polarization (IP), seismic
refraction and reflection, ground penetrating radar (GPR) and geological field mapping.
The geophysical anomalies obtained for the known cave were extrapolated to other parts
of the hill, revealing the presence of new cavities. In addition, the sensitivity of each
geophysical method for detecting caves in metallic mineralized sectors was analysed.
Regarding microgravity prospection, a detailed analysis of already available regionalresidual
anomaly separation methods was carried out. High resolution residual gravity
maps were obtained by means of first order polynomial fitting. Meanwhile, the Algaidilla
cave (Estepa, Southern Spain), partially saturated with salty water and enclosed in
carbonates disconnected from the surface, was studied through microgravity, ERT and IP
methods. Joint interpretation made it possible to derive the approximate morphology of
the cavity. Finally, a combination of microgravity and ERT techniques in 3D array were
applied over the shallow gypsum caves of Sorbas (Almería, SE Spain); the measurements
repeated in time-lapse allow these geophysical methods to be tested in sectors having a
low contrast in physical parameters. Application of the geophysical techniques in
different contexts leads to the conclusion that microgravity and ray tracing coverage in
seismic refraction are, in general, the most suitable methodologies for cave detection.